Split from drone thread.

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large_ghostman

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Slightly more serious discussion on some the points that came up in the swarm thread.

So for now lets assume a swarm wants to find you and you dont want to be found. The idea is to look at things that may actually be an issue if you were searching for someone, although in this case they would likely want to be found, it makes sense to do it the other way.

I thought alot about the answers from the other thread, most are not really issue. Details as we go but the swarm is a real mesh network system with multi master.

We will assume all tech used is available to the public or at a push to normal rescue/ law enforcement, as we dont have them in the UK no feds or MI5 etc.
After i did my last drone i didnt keep up too much with the tech as such, looking at it now, there is way more i could do now that wasnt really possible then.
I think if you used correctly drones have real potential, so i am going back in my spare time to work on it.

Although my actual start point will be going back to look at fuel and generators for longer flight times. One reason being I have several hundred ltrs of methanol and the engines etc etc and i still have alot of the dev boards and radio kit. So while money is tight (being spent on my business) i am starting at the least expensive bit for me.

Depending how the engine turns out i would like to aim for a hexa copter again, previously the ones i did way out performed the quads but the cost is energy.
 
I got stuff all over the place from my drones (pics and paperwork), I will dump some here ready to organize it. The boards i used originally for motor control development were some silicon labs ones like in the picture. i still have a couple, while the motors have some serious power i am sure there are now way better ones on the market, but for software development i might use the boards and swap the motors out if needed. The other pic i found was something i played with, the idea was to use a piezo transducer to detect top and bottom stroke.

The engine is a very small glow engine, this was the start of seeing if i could get a glow engine to run on petrol without alot of complicated mods. I didnt go this way in the end, but i did find that it was a good way to see when an engine was well tuned. I also managed to easily detect top and bottom stroke using it and oscilloscope. I will be using a bigger engine this time, but i might still use the piezo and scope for tuning up. I used washers in the end to pinch the disk to the casing via the screws in the case.

I dont have any of the drone stuff on mendely software, so its a bit of a hunting game, i do have an excellent file and document server now thats made for document control and sharing, so as i find relevant things i will put them in there and link directly.

 
The radio dev kits are superb, the radio transceiver chip also has a built in 32 bit micro, the borad looks chuncky but actually the module separates into a tiny square, as you can see in these pics, i used the main dev kits for the initial dev work then used another micro board which ended being the actual drone brain. The one I used had a ARM M4 core and 1 gig memory. this time i will likely use several different coms including very long range bluetooth.

The radio chips really are the Biz, I have had 6KM out of them with pretty low power. They have some newer chips both for the main control and for radio transceivers, I might see if they will send me a couple to review, but its likely the initial work will be done on these again.
I cant find the main radio dev kit pics i had, i will post those tomorrow when i find them.
 

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dknguyen said:
Wow, I didn't know they made outrunners that small.
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It could be my picture taking skills, they are not that small, but they do have some serious power. really good motors, I used 6 and apart from the power they used, they could do some serious lifting. Blade tech has also got better.

initial drone build will be balsawood made into plywood, i wont go straight to carbon it takes too long. And for testing i found alternate lap balsa sheets works fine.
 
Maybe the sense of scaling is all off because it's a photo. It looks reasonable size when I compare it to the barrel jack connector but it looks 15mm in diameter when I compare it to the TSSOPs.
 
No they are way bigger than 15mm, so its my bad picture skills i will take better pictures anyway, these are just me plonking things where i can find then easily.
 

Honestly, I was rather impressed when I saw a wood quadcopter frame. I think you can apparently can significantly lower weight than carbon but have it be strong enough since you can reasonably use thicker material stiff so it has higher bending stiffness. Also has better vibration dampening than carbon and cheaper.

If I made a quadcopter frame I would try to sandwich thin carbon layer around some foam to try and make a quadcopter frame that is essentially foam. Not sure how well that would work.

Why wouldn't you just stick with balsa plywood as the last stage? My understanding is you have to make your own balsa plywood anyways so if that's the case you can fabricate whatever thickness you want. And if you're SUPER into it, you can apply a super thin layer of glass or carbon to both sides of the balsa plywood, far thinner than what you would find in a prepeg carbon plate. That'd be far superior.
 
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I made my turbine data plane (it was for reading data from hard to reach wind turbines) from balsa, i used extremely thin balsa sheet.

One side was straight grain then i alternated the grain at 45 degrees ish all along both sides but going different directions and like mini triangles, extremely strong and light but takes ages. For quick prototypes i simply put one sheet with the grain one way then a layer with it in the other direction (so vertical and then horizontal). The main reason the finished one would be carbon is for heat in a burning building.

I dont do normal shape quad copters and this time i might push the envelope even more, mainly its speed of working in balsa for prototypes and cost, doing light carbon fiber costs a fortune and takes ages to do. As this is a rescue swarm I will also be doing a different one, a bit like a large mother ship but without alot of the functions of the others, this is based on pommies scenario of lost people, we dont have the outback but we get people lost on the hills and mountains.

So the idea would be a large drone with basic systems in, most the weight would be things like carrying a med kit and water etc. it would sit in the center of the search area on the ground in idle mode, any message from the swarm saying its found someone and needs helps it would goto the area. Not totally sure yet, just looking at ideas.

Biggest change will be looking at the fly boards you can get now, back when i did mine you had to build your own, i still might hand roll depending how flexible the standard boards are. I am about 40% done on the site for the projects. if i get time to finish the project then the site will also become the control center. Looking at newer motors i can see lighter ones with more oomph and less power. Blades is another area to look at.
 
If it's hot enough to mess with the wood, would it not have gotten hot enough earlier to mess with the motor magnets and batteries) first (or maybe even the electronics)?
 
dknguyen said:
If it's hot enough to mess with the wood, would it not have gotten hot enough earlier to mess with the motor magnets and batteries) first (or maybe even the electronics)?
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I now have a new pc, with some really great free software designed to organize and reference papers etc, but back when i did this project a couple of years ago (more like maybe 3??) I didnt i had a laptop. I did the project at school to get a university place 2 years early, then decided i didnt want to go. I left the files on the hard drive and forgot all about it...

I had wrongly assumed i had finally updated the project with the final video and details etc, i couldnt at the time because it was school stuff and they wouldnt allow me to youtube it. Right so to the point, my scenario was a mocked up burning building but we didnt have flames, we did have dry ice smoke and hot water bottles to try and fool the vision system. The carbon fiber was fine in flames and the props were made from graphite, the motors were inside and drive driven not direct shaft driven.

The material used in school metal work brazing forges and household gas fires was used as a heat shield where needed, its extremely light weight and if you spend 4 weeks with a dremel and sand paper, then you can build decent heat shields. But it was never tested in fire, so i cant answer the question. It could fly quickly and did have IR temp sensing, my gut feeling is you could negate a great deal of temperature. In the 9 odd months i spent on it i did go through these problems but the school was never going to let me set fire to it, i wasnt allowed to do it outside.

But realistically to a greater extent you can avoid very high temp areas, your not likely to find life there. So its short periods of passing through high temps or backtracking and finding another way in. Balsa is a good material but its main use is speed of prototype, i found i had to change the frame alot. I am looking for the videos and files which will explain things better, this wasnt the normal X shape frame. I custom made it for a specific purpose and only had enough school funds to get two shots at carbon fiber, so i got used to tweaking and building in wood first.

Once i was sure i had the final design i used Carbon, but it takes around 2 weeks to build with carbon fiber and roughly 4 -9 hours with balsa. This time i might go the ceramic sponge route for filling a hollow carbon body.

the props i call graphite, but they were made by my tech teacher, they contained mostly graphite with some kind of binding material, I dont know what it was but i know it would of been in the materials list. So once i find it i will let you know.

i can also tell you how much weight you save with carbon fiber, i fought for every gram on that thing!! Now none of this is intended to say your wrong, on the contrary. The more you question it the more i will look into the best material, this one isnt a toy to get me into uni. Back then i thought drones might have a use some day, but then you couldnt buy them pre made easily they were around £2,500 for what would cost you £150 now.

So maybe the time for them has come, i stayed away from the 2 gig frequency i used two sub gig ones, one is used in America normally and one was mainly supposed to be used for smart meters. back then smart meters were not being used in the real world, so it was ideal. The radio transceiver chips were really good with built in quality micros, even these have been updated to another level but i will use the old dev kits i have for now. I could get 8 hours of life out two cheap AA batteries and power the radio gear including video streams. So i am 100% positive we could pull this off, my main sticking point was every man and his dog telling me a 2 stroke glow engine could run on petrol unmodified.

Worse than that I was told it could power a generator with enough power for the motors, both of these things i did not that long ago for another project. My main sticking point is time. i was a kid back then and at school, now i have a house i got to provide for and three businesses to run. But my heart says this is worth doing, especially given some the talent on here. I dont have the brains to pull it off on my own, but i am not on my own.

i will start with a pi2 again, then get the pi3, the 3 has a massive advantage over the 2, the pi2 was always a weak point but the new pi3 addresses these problem. i dont think the modern flight control boards are upto it, i still think these need hand building again. but it isnt that hard in reality.
 
What's ceramic sponge?

I've not been in a fire either so I have no idea how hot it is. I'm just thinking that epoxy gets soft but wood does [???] and before bursting into flames, but somehow I'm thinking that wood bursts into flames at a higher temperature than the glass temperature of the epoxy in normal composites.
 

Have you ever seen those very light weight white fire bricks? similar to what you get in a household gas fire as a back plate? Ceramic sponge is similar except there seems to be alot more holes, its extremely fire proof and dosnt get hot the other side.

The other idea is obviously use MIMS cable or cabel similar to that used with thermo couples. The biggest issue with heat is finding people, IR is out to a certain extent and makes vision systems difficult. Because i couldnt use real fire i didnt get a chance to really look into it.

the new library system for vision i have seen, also has UV range. That with shape building is likely the start point, testing fire here is not so hard. Mock up a house with old straw bales and set fire to some, apart from detecting people fire dosnt worry me so much, Carbon fiber can take a fair amount of heat, most the systems are inside the drone out the way. While it weighs a little more, Vermiculite poured into the voids does a pretty good job.

Balsa is very strong is done as alternating cross ply on straight sheets, but its a fair bit weaker than carbon fiber. Where is comes into its own is crash repair while testing, its very very quick. if you add fiber glass to it and resin, the weight starts to climb fairly rapidly.

I ended up literally weighing things down to 0.5g to shave as much weight as I could, the issue i had was batteries. The ones I used were a fair bit of money, the next ones up were over £300 each at the time. I got 9 mins fly time out of my batteries, although there is a company that does ultra thin ones now, batteries are really a kind of last ditch land in emergency. We are aiming for 1-2 hour flight times minimum, so batteries are out. You end up using so many you cant carry much else.

Again however its a learning curve, i am surprised just how much the tech has moved on, some of the new multi protocol transceiver chips are excellent, especially with true mesh capability. First job is to look at the engine side and fuel / generator, I might try and get the non sponge heat material and see what its like as a prop, under slow motion video you see many other props flex at high speed, you loose alot of the lift with that.
 
Started to find pics and files in various dark corners of HDD's!
These are some the model engines i collected for tested. The GMS engine with the gold top, thats the one i am likely to start with. I am told they are not that great but this one hasnt been run in yet, so i will give it a go.
 
It's only an idea and you may have already though about/discounted this, but what about using balsa as a form, then wrapping a couple of cross-woven layers of carbon fiber over it?
 
thats similar to how the final was done.

balsa i use while experimenting, i notice now you can buy drone bases, that wasnt an option back then, but they are pretty much the same standard shapes, a bit like a squashed X, Hence if you spread the X shape out more and add a prop top and bottom center of the opened X you get a better flight and can move in tighter spots.

The way it was done last time was a balsa frame as a mold, this was cast then a wax like frame built (its not wax but very similar). the carbon fiber sheets are laid over this, eventually all you then do is heat the material so the former kind of melt leaving a hollow carbon fiber frame. Until i find the folder i cant be sure, but weight wise you gain roughly 90% weight loss. Does it matter? I dont honestly know, back then i had 9 mins of flight time to do a task that was averaging just a tad over 10 mins!
So it got to the point where we would peel labels off of things to loose weight , as it turned out we did the three runs and had roughly 20 seconds flight time left. This is a different situation, but i wont be making it from carbon fiber until the final prototype.

I can use Balsa all the way until the very very last prototype. Also this time we are aiming for more weight capacity and longer flight times. So it depends how well we can get a generator to work, once you hot 1-2 hours flight time then loosing 10 mins to weight isnt a deal breaker. On this one i wont be doing the final frame, i will get that made for me and have it made hollow. You always get a couple of last min wires you didnt think of, drilling a hole and pulling through a frame is a bonus . Not even dure what size it would be yet.

Pommie was looking at much larger engines than i did, so at least for now I want to see what can be done with really small scale high capacity. But plain balsa with maybe some varnish is fine for 80% of the testing. Its way later i would start to think about Carbon fiber, the cost is horrific.

Fire isnt the main reason for Carbon fiber, its just a really tough material. For now i might even use a 3D printer for the initial mock ups of the frames, but having access to a laser cnc that cuts balsa, it makes sense to use it for the initial trials on shape.

Looking at some papers on computer vision, some interesting techniques being used in last 12 months. There used to be a place in China on ebay, you gave them the laptop model and they supplied an interface for the tiny camera. They seem long gone , little laptop cameras using the old Matlab vision lib worked well for shape vision. maybe i will focus more on the material once i get an idea what motors are about now and the generator needed, then i can work out size and capacity from there. Then i will start to worry about material being used.

Is a way off yet.
 
How would you detect something like a 100lb breaking strain, clear nylon fishing type net? I got 80lb line and diameter is 0.45mm. This is leader type line so no idea if its thick or thin for the breaking strain, but at 7 feet or more i cant see it at all if its placed across a room.

So lets say you made a net with 12-14 inch holes in, i cant think of an easy way to detect it at say 10-15 feet with a drone, you might get lucky with colour difference but unlikely. I discounted the bumper radar system because in most systems the way you avoid things could be overcome by how a net was placed.

Radio?? Dont know enough to begin to guess if there is anything that way. IR scatter might work at night but again your up against how the net is placed. Admittedly unless your scouting a fire in a fishing net factory it isnt a likely obstacle .
 
dknguyen said:
But the resin binder, not the fibers is the limiting factor for composites and always have been.
Click to expand...
That still gives you around 180-200C with a half decent resin, plus your not stationary. Biggest factor is strength and being able to have voids, to start with the prototypes are heavily restricted temperature wise because of the 3D printer parts. Carbon fiber is also conductive which might be useful for an idea spinning around my head.

Whatever happens i wont be paying for more than one or two CF prototypes! Most of the testing can be done with Balsa. Still hunting for my project folder with all the printed out stuff I had, starting to get that really bad feeling I left it at school or chucked it out!! Unlikely but I have looked everywhere i would of normally put something like that. Not much I can do at the moment, i need to save for a 4 stroke engine, unless i make do for now with a glow conversion.

But having seen the figures for the OS engines, unless I can get a decent sized diesel (very unlikely they do them that size), then it makes sense to go with the 4 stroke. It isnt a high priority at the moment, i got alot of work on and little spare time.
 
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